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<meta name="description" content="Tom's Audio Processing plugins for
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audio engineering on the Linux platform.">
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<meta name="keywords" content="TAP-plugins TAP Reverb Editor
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Reverberator Equalizer EQ Vibrato Tremolo Echo Tom Szilagyi LADSPA
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JACK Plugin Linux Audio">
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<meta name="author" content="Tom Szilagyi">
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<font size="+2" color=#004060><b>TAP</b>-plugins</font><br>
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<font color=#004060>Tom's Audio Processing plugins</font><br>
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<font size="-1" color=#004060><i>for audio engineering on the Linux
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<a href="../index.html">[ Home ]</a>
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<a href="../ladspa.html">[ LADSPA plugins ]</a>
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<a href="../reverbed.html">[ TAP Reverb Editor ]</a>
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<a href="releases.html">[ Releases ]</a>
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<a href="cvs.html">[ CVS ]</a>
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<a href="general.html">[ General Info ]</a>
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<a href="manuals.html">[ Plugin Manuals ]</a>
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<a href="autopan.html">[ TAP AutoPanner ]</a>
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<a href="chorusflanger.html">[ TAP Chorus/Flanger ]</a>
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<a href="deesser.html">[ TAP DeEsser ]</a>
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<a href="dynamics.html">[ TAP Dynamics (Mono & Stereo) ]</a>
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<a href="eq.html">[ TAP Equalizer and TAP Equalizer/BW ]</a>
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<a href="doubler.html">[ TAP Fractal Doubler ]</a>
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<a href="pinknoise.html">[ TAP Pink/Fractal Noise ]</a>
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<a href="pitch.html">[ TAP Pitch Shifter ]</a>
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<a href="reflector.html">[ TAP Reflector ]</a>
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<a href="reverb.html">[ TAP Reverberator ]</a>
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<a href="rotspeak.html">[ TAP Rotary Speaker ]</a>
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<a href="limiter.html">[ TAP Scaling Limiter ]</a>
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<a href="sigmoid.html">[ TAP Sigmoid Booster ]</a>
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<a href="echo.html">[ TAP Stereo Echo ]</a>
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<a href="tremolo.html">[ TAP Tremolo ]</a>
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<a href="tubewarmth.html">[ TAP TubeWarmth ]</a>
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<a href="vibrato.html">[ TAP Vibrato ]</a>
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<h2>TAP Equalizer</h2>
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and <b>TAP Equalizer/BW</b><br><br><br>
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<img src="tap_eq.png" alt="[TAP Equalizer GUI as shown in Ardour]">
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This plugin is an 8-band equalizer with adjustable band center
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frequencies. It allows you to make precise adjustments to the tonal
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coloration of your tracks. The design and code of this plugin is based
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on that of the DJ EQ plugin by Steve Harris, which can be downloaded
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(among lots of other useful plugins) from <a
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href="http://plugin.org.uk">http://plugin.org.uk</a>.
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<h3>General information</h3>
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<table cellspacing="0" cellpadding="5" border="1">
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<tr><th align="left">Unique ID</th><td>2141 [1]</td>
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<tr><th align="left">I/O ports</th><td>1 input / 1 output</td>
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<tr><th align="left">CPU usage (44.1 kHz)</th><td>4.0% max. (see Notes)</td>
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<tr><th align="left">CPU usage (96 kHz)</th><td>8.8% max. (see Notes)</td>
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<tr><th align="left">Hard RT Capable</th><td>No</td></tr>
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<tr><th align="left">In-place operation</th><td>Supported</td>
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<tr><th align="left">run_adding() function</th><td>Provided</td>
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[1] Unique ID for TAP Equalizer/BW is 2151.<br>
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The TAP Equalizer is a powerful tool in the hands of a skilled mixing
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engineer. The main use of the band frequency controls is to allow to
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"tune in" various resonance frequencies of musical instruments, and by
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adjusting the gain of these frequencies, to alter the tone of an
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instrument in a desired way. For example, the sound of kick drums
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consists of two mainly distinct parts: the energy is mainly
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concentrated around 80-100 Hz (this is the "boom" part), but there is
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another component at around 2.5 kHz which gives the "edge" of the
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sound. By adjusting the level of these components, different tonal
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results can be achieved.
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While listening to the track (soloed or not) with this plugin applied,
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raise the gain of the appropriate band (that is, the one with the
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closest default frequency) by an amount of about 6-12 dB and adjust
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the frequency control of the same band until you feel that you "got"
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that particular resonant tone of the instrument. Then play around with
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the gain settings to achieve the tonal balance you are going for.
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Since you only pay (in terms of CPU usage) for the bands you actually
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use, it is recommended that you set the gains of unneeded bands to
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exactly 0 dB (you can do this in Ardour quickly by shift+clicking on
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the control fader) since processing of bands with 0 dB gain will be
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skipped. So don't leave a band gain at -0.12 dB unless you really need
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that -0.12 dB to be there.
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<h3>Summary of user controls</h3>
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<table cellspacing="0" cellpadding="5" border="1">
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<tr><th>name</th><th>min. value</th><th>default value</th><th>max. value</th></tr>
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<tr align="center"><td>Band 1 Freq [Hz]</td>
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<tr align="center"><td>Band 1 Gain [dB]</td>
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<tr align="center"><td>Band 1 Bandwidth [octaves] [2]</td>
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<tr align="center"><td>Band 2 Freq [Hz]</td>
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<tr align="center"><td>Band 2 Gain [dB]</td>
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<tr align="center"><td>Band 2 Bandwidth [octaves] [2]</td>
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<tr align="center"><td>Band 3 Freq [Hz]</td>
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<tr align="center"><td>Band 3 Gain [dB]</td>
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<tr align="center"><td>Band 3 Bandwidth [octaves] [2]</td>
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<tr align="center"><td>Band 4 Freq [Hz]</td>
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<tr align="center"><td>Band 4 Gain [dB]</td>
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<tr align="center"><td>Band 4 Bandwidth [octaves] [2]</td>
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<tr align="center"><td>Band 5 Freq [Hz]</td>
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<tr align="center"><td>Band 5 Gain [dB]</td>
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<tr align="center"><td>Band 5 Bandwidth [octaves] [2]</td>
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<tr align="center"><td>Band 6 Freq [Hz]</td>
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<tr align="center"><td>Band 6 Gain [dB]</td>
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<tr align="center"><td>Band 6 Bandwidth [octaves] [2]</td>
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<tr align="center"><td>Band 7 Freq [Hz]</td>
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<tr align="center"><td>Band 7 Gain [dB]</td>
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<tr align="center"><td>Band 7 Bandwidth [octaves] [2]</td>
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<tr align="center"><td>Band 8 Freq [Hz]</td>
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<tr align="center"><td>Band 8 Gain [dB]</td>
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<tr align="center"><td>Band 8 Bandwidth [octaves] [2]</td>
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[2] These controls appear only in the TAP Equalizer/BW implementation.<br>
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This plugin consists of 8 Peaking EQ filters (which are IIR filters
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with an order of two). Filter coefficients are re-computed if and only
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if the user changed a control value since the last buffer
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run. Furthermore, those filters that are left at 0 dB gain are not
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processed at all. For this reason, the CPU demand of this plugin is a
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function of the control settings, hence it is not hard RT
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capable. However, the CPU demand is still somewhat predictable: moving
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all gains away from 0 dB will switch every filter on. The CPU usage
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measured in this state will not increase significantly when filter
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coefficients are re-computed in response to a changed control. Of
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course, if the user sets a gain back to 0 dB, that filter will be
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switched off, freeing CPU power. The CPU usage values displayed in the
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above table were measured with all filters working.
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The bandwidth of the Peaking EQ filters is fixed to 1 octave in the
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TAP Equalizer implementation. However, because setting individual
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bandwidth values may be needed in certain cases, another
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implementation called TAP Equalizer/BW is also provided. Using that
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plugin, you can set the bandwidth of every filter between 0.1 and 5
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octaves. The reason for keeping TAP Equalizer around as well is that
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you don't always need the ability to set bandwidth values, and TAP
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Equalizer/BW has a large amount of controls which may be disturbing in
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Below you can see a Bode diagram of the filter that makes up this
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plugin. The three frequencies are 100 Hz, 1 kHz and 10 kHz, with gain
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values of -20 and +20 dB and a sampling rate of 44.1 kHz. Bandwidth
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was set to 1 octave (which is the default). This plot is also
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available as an <a href="tap_eq_bode.eps">EPS file</a>.
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<img src="tap_eq_bode.png" alt="[TAP Equalizer filter Bode diagram]">
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$Id: eq.html,v 1.3 2004/08/17 13:05:16 tszilagyi Exp $
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